This invention relates to a thermometry device and more particularly to a thermometry device which embodies an electronic calculator system. A digital electronic thermometer commonly includes a thermistor as a thermometry resistor whose resistance value varies depending upon temperature.
As suggested in Japanese Patent Kokai No. 53-69685, corresponding to U.S. Pat. No. 4,150,573, another well known device includes a reference resistor and a thermometry device.
In the device of this patent an oscillator is provided whose oscillation frequency vaires in proportion or in inverse proportion to the value of the selected resistor, thus making resistance variations in the thermometry resistor substantially linearly proportional to temperature. Output pulses from the oscillator are counted within a predetermined limited period of time to restrain thermometry within a range covering from 35.degree. to 45.degree. C.
The temperature dependency of the resistance of the thermistor in the conventional device is inaccurate and does not have a linear relationship in a wide temperature range, thus requiring complex arithmetic logic processes.
In the case where the output pulses of the oscillator are counted within the limited period of time, additional hardware such as a counter is required and it is very difficult to set up the thermometry device with cost savings.